Liquid crystals are often employed in devices, such as liquid crystal displays (LCDs), which utilize the different optical properties of liquid crystalline molecules in either the presence or absence of, for example, an electric field. In one example, the liquid crystal material may be oriented in one liquid crystal phase in the absence of an electric field, wherein light is transmitted through the device and reflected back to the observer such that the device appears clear. The liquid crystal material may be reoriented in a different liquid crystal phase in the presence of an electric field, wherein light is no longer transmitted through the device such that the device appears dark. Thus, an electric field may be applied to switch the liquid crystal material between clear and dark (e.g., “on” and “off” states). In LCDs, images may be created using a plurality of individual picture elements or “pixels,” wherein each pixel may contain a liquid crystal material which may be switched to form the image. In color LCDs, color filters or chromophores such as dyes may be incorporated within the device to generate the appearance of color within each pixel.
In many present day LCDs, the alignment of the liquid crystal material in the absence of an electric field may be determined by a surface in contact with the liquid crystal. The surface may be rubbed or otherwise treated such that the surface can orient the liquid crystal material in the absence of the electric field. In the presence of an electric field, the liquid crystal material may be switched to one state (e.g., “turn-on” event), and, upon subsequent removal of the electric field, the liquid crystal material may relax or decay to its original state (e.g., “turn-off” event). In such cases, the “turn-on” event may be fast because the switching of the liquid crystal is actively driven by an electric field. However, the “turn-off” event may be slow because the realignment of the liquid crystal by the treated surface often begins at the surface and must propagate into the bulk of the liquid crystal material. Additionally, many LCDs require an active electric field to keep the liquid crystal material in one of the two states (e.g., “on” or “off”), resulting in the need for a constant source of external energy.
Accordingly, improved devices and methods are needed.